Conventionally, a storage case has been known, which includes a case main body having upper and front surfaces being opened, and a cover body having upper and front covers which cover the upper and front surfaces of the case main body, respectively. The front cover is connected to the upper cover through a hinge and is hung from the upper cover. The front cover is turned upward/downward between a closed state and an opened state to open/close the storage case.
In such a storage case, in order to hold the front cover in a state where the front cover is turned upward and raised, a locking projection and an engagement member are provided in a hinge structure between the front cover and the upper cover. When the front cover is turned upward and raised to a predetermined angle, the locking projection comes into contact with the engagement member. When the front cover is further turned upward from the predetermined angle so that the locking projection passes over the engagement member, and then afterward the front cover is not able to return (to be turned downward) to the closed state by a self-weight of the front cover (see, for example, Japanese Patent No. 5721688).
Specifically, in the storage case described in Japanese Patent No. 5721688, in the hinge structure between the upper cover and the front cover, the locking projection is formed on the front cover and a projection is also provided on the upper cover as the engagement member. When the front cover is turned upward to the predetermined angle, the locking projection passes over the engagement member and engages with the engagement member. Thereby, the front cover is prevented from being turned downward and being closed by the self-weight and the front cover can be held in the opened state.
Similarly, Japan Patent No. 3161698 discloses a container having a turnable upper cover, and a hinge structure capable of holding the upper cover in an opened state.